The invention relates to a driving and metering device for an injection device for administering a liquid product, particularly a medicine such as insulin. A product dose to be administered can be set and preferably dispensed with the driving and metering device, wherein these steps can be repeated multiple times. The invention thus also relates to an injection device having such a driving and metering device.
From the prior art, particularly WO 2009/105909 A1, an injection device is known that has a housing in which is arranged a dosage display sleeve with a helical scale arranged over the circumference thereof. A rotatable metering button that is axially fixed in relation to the housing is arranged at the rear end of the housing. By rotating the metering button, the dosage display drum is screwed along a thread formed on the housing. The thread has the same pitch as the helical scale on the circumference of the dosage display element.
WO 2005/046770 A1 describes an injection device having an adjusting element at the distal end thereof that is used for setting the injection dosage. The adjusting element further comprises a helical dosage scale. The adjusting element is in threaded engagement with the housing via a first thread and, via a second thread, with a slide that is rotationally fixed in relation to the housing but is axially movable. The thread for the threaded engagement with the housing has a pitch equal to that of the helical dosage scale, while the thread for the engagement with the slide has a smaller pitch than that of the dosage scale.
The devices known from the prior art are quite challenging in regard to assembly. In particular, it is necessary to bring the adjusting element into engagement with two threads of different pitches during assembly in WO 2005/046770 A1.